This application claims the priority of German Application No. 100 41 894.5 filed Aug. 25, 2000, which is incorporated herein by reference.
This invention relates to a method of directly determining setting values for the application point of regulation in a regulated draw frame for fiber material. The control system of the draw frame in which the extent of draft of the sliver may be set has at least one preliminary control system for changing the draft of the sliver. Based on the drafted sliver, a number of quality-characterizing measured values, such as CV values may be sensed and utilized for formulating a function whose minimum represents an optimum application point of regulation for the control of the draw frame. The optimized application point of regulation may be determined in a pre-operational test run or a setting run of the draw frame.
The application point of regulation is an important setting magnitude in a draw frame to produce slivers with a high sliver uniformity, that is, with a small CV value.
In a known system, during a pre-operational setting run, the sliver is drafted between the mid rolls and the output rolls of the draw unit and is withdrawn by calender rolls which are adjoined by a measuring device for the CV value of the drafted sliver. In the pre-operational setting run a plurality of CV values are determined which represent a quality-characterizing magnitude for the drafted sliver. Based on such measured values, a function is formulated whose minimum value corresponds to a value which promises to be the best adaptation of the regulation actual sliver. The plurality of measured values which are plotted and based on which the function is formulated, are in each instance measured for a different setting value of the regulation. Thus, for the definition of the function to be evaluated, each incremental value of an incrementally changing parameter, for example, the application point of regulation of the xe2x80x9celectronic memoryxe2x80x9d, has to be associated with one of the measured values.
It is a disadvantage of the above-outlined system that the quality of the un-drafted sliver entering the draw unit cannot be taken into consideration. It is a further drawback that only one certain CV value is considered.
It is an object of the invention to provide a method of the above-outlined type from which the discussed disadvantages are eliminated and which in particular improves the determination and setting of the optimal application point of regulation in a regulating device of the draw unit.
This object and others to become apparent as the specification progresses, are accomplished by the invention, according to which, briefly stated, the method of directly determining setting values for an application point of regulation in a draw unit for drafting sliver includes the following steps: obtaining a plurality of measured values of a quality-characterizing magnitude, such as a CV value, of the drafted sliver; utilizing the measured values for formulating a function having a minimum constituting an optimal application point of regulation for controlling the draw unit; determining the optimal application point of regulation in a pre-operational run of the draw unit; obtaining measured values of at least two quality-characterizing magnitudes based on the drafted sliver; combining values of the quality-characterizing magnitudes at the sliver, which correspond to one another with respect to the application point of regulation, to a quality-characterizing number QK, and forming a function based on several numbers QK. The function has a minimum corresponding to an optimal application point of regulation Ropt.
The optimal application point of regulation (optimal dead period or delay) is determined by the draw frame itself by using the steps according to the invention. By utilizing different quality-characterizing magnitudes, such as CV values, the application point of regulation is determined in a more accurate manner. Further, a more rapid determination of the application point of regulation is made possible.